U.S. patent number 9,456,329 [Application Number 13/522,012] was granted by the patent office on 2016-09-27 for method and apparatus for disabling an illegal device in a wireless lan system.
This patent grant is currently assigned to LG ELECTRONICS INC.. The grantee listed for this patent is Eunsun Kim, Jihyun Lee, Yongho Seok. Invention is credited to Eunsun Kim, Jihyun Lee, Yongho Seok.
United States Patent |
9,456,329 |
Seok , et al. |
September 27, 2016 |
Method and apparatus for disabling an illegal device in a wireless
LAN system
Abstract
A method for an enabler entity to indicate an event to a manager
entity includes transmitting, from the enabler entity to the
manager entity, an event indication message indicating an event in
a device served by the enabler entity. The enabler entity enables
communication between the device and the manager entity and the
manager entity exchanges information required for coexistence
between enabler entities comprising the enabler entity. The event
indication message includes type information indicating that the
event indication message is for indicating that a specific device
is detected by the device, the specific device operating on a
frequency not permitted to the specific device.
Inventors: |
Seok; Yongho (Anyang-si,
KR), Lee; Jihyun (Anyang-si, KR), Kim;
Eunsun (Anyang-si, KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
Seok; Yongho
Lee; Jihyun
Kim; Eunsun |
Anyang-si
Anyang-si
Anyang-si |
N/A
N/A
N/A |
KR
KR
KR |
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Assignee: |
LG ELECTRONICS INC. (Seoul,
KR)
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Family
ID: |
45874248 |
Appl.
No.: |
13/522,012 |
Filed: |
September 20, 2011 |
PCT
Filed: |
September 20, 2011 |
PCT No.: |
PCT/KR2011/006931 |
371(c)(1),(2),(4) Date: |
July 12, 2012 |
PCT
Pub. No.: |
WO2012/039574 |
PCT
Pub. Date: |
March 29, 2012 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20130163574 A1 |
Jun 27, 2013 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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61384316 |
Sep 20, 2010 |
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61387973 |
Sep 29, 2010 |
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61391072 |
Oct 7, 2010 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W
8/005 (20130101); H04W 12/084 (20210101); H04W
84/12 (20130101); H04W 16/14 (20130101); H04W
48/16 (20130101) |
Current International
Class: |
H04W
12/08 (20090101); H04W 8/00 (20090101); H04W
16/14 (20090101); H04W 84/12 (20090101); H04W
48/16 (20090101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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101167377 |
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Apr 2008 |
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CN |
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101277229 |
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Oct 2008 |
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CN |
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2006/102793 |
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Oct 2006 |
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WO |
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Other References
Yonghong Zeng et al., "Worldwide Regulatory and Standardization
Activities on Cognitive Radio", IEEE Symposium on New Frontiers in
Dynamic Spectrum, pp. 1-9, Apr. 2010. cited by applicant .
Maziar Nekovee, "A survey of cognitive radio access to TV White
Spaces", ICUMT, pp. 1-8, Oct. 2009. cited by applicant .
Kim, et al., "Comment Discussion on map and enablement," IEEE
P802.11 Wireless LANs, doc.: IEEE 802.11-10/1041r0, Sep. 2010, 8
pages. cited by applicant .
Kim, et al., "Normative Text for White Space Map," IEEE P802.11
Wireless LANs, doc.: IEEE 802.11-10/0790r2, Jul. 2010, 20 pages.
cited by applicant .
Kang, et al., "System description and reference model proposal,"
IEEE P802.19 Wireless Coexistence, doc.: IEEE 802.19-10/0113r2,
Sep. 2010, 28 pages. cited by applicant .
Kasslin, et al., Coexistence architecture of 802.19.1, doc.: IEEE
802.19-10/0013r0, Jan. 2010, 12 pages. cited by applicant .
Kim, et al., "TVWS Enablement Scenarios," doc.: IEEE
802.11-10/0720r0, Jun. 2010, 13 pages. cited by applicant .
Ruuska, et al., "P802.19.1 System Architecture," doc.: IEEE
802.19-10/0046r3, Mar. 2010, 23 pages. cited by applicant.
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Primary Examiner: Vu; Huy D
Assistant Examiner: Nguyen; Bao G
Attorney, Agent or Firm: Lee, Hong, Degerman, Kang &
Walmey Kang; Jonathan Monaco; Michael
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is the National Stage filing under 35 U.S.C. 371
of International Application No. PCT/KR2011/006931, filed on Sep.
20, 2011, which claims the benefit of U.S. Provisional Application
Ser. No. 61/391,072, filed on Oct. 7, 2010, 61/387,973, filed on
Sep. 29, 2010, and 61/384,316, filed on Sep. 20, 2010, the contents
of which are all incorporated by reference herein in their
entirety.
Claims
The invention claimed is:
1. A method for an enabler entity to indicate an event to a manager
entity, the method comprising: receiving, from a first unlicensed
device served by the enabler entity, a report message reporting an
illegal device detection event in the first unlicensed device; and
transmitting, from the enabler entity to the manager entity, an
event indication message indicating the illegal device detection
event in the first unlicensed device served by the enabler entity,
wherein the enabler entity enables communication between the first
unlicensed device and the manager entity, wherein the manager
entity exchanges information required for coexistence between
enabler entities comprising the enabler entity, wherein the event
indication message comprises: type information indicating that the
event indication message is for indicating that a second unlicensed
device is detected by the first unlicensed device, the second
unlicensed device operating on a licensed TV frequency not
permitted to the second unlicensed device and without complying
with regulations, and the first unlicensed device operating on the
licensed TV frequency with permission and under the regulations,
wherein whether the second unlicensed device complies with the
regulations is determined in consideration of whether the second
unlicensed device is a fixed type device or a portable type device,
and wherein the illegal device detection event in the first
unlicensed device is reported only when the first unlicensed device
and the second device belong to a same type.
2. The method of claim 1, wherein the event indication message
further comprises: an identification information of the second
unlicensed device; and a channel number on which the second
unlicensed device is operating.
3. The method of claim 1, wherein the enabler entity comprises a
coexistence enabler (CE), and the manager entity comprises a
coexistence manager (CM).
4. The method of claim 1, wherein the first unlicensed device and
the second unlicensed device comprise a television band device
(TVBD).
5. The method of claim 1, wherein the event indication message
transmitted from the enabler entity to the manager entity is
transmitted when the second unlicensed device is not served by the
enabler entity.
6. The method of claim 1, wherein the event indication message
further comprises: a source identifier indicating an identifier of
the enabler entity; and a destination identifier indicating an
identifier of the manager entity.
7. An enabler entity indicating an event to a manager entity, the
enabler entity comprising: a radio frequency (RF) unit configured
to receive, from a first unlicensed device served by the enabler
entity, a report message reporting an illegal device detection
event in the first unlicensed device; and a processor configured to
generate an event indication message indicating an event in a first
unlicensed device served by the enabler entity, and control the RF
unit to transmit the event indication message to the manager
entity, wherein the enabler entity enables communication between
the first unlicensed device and the manager entity and the manager
entity exchanges information required for coexistence between
enabler entities comprising the enabler entity, wherein the event
indication message comprises: type information indicating that the
event indication message is for indicating that a second unlicensed
device is detected by the first unlicensed device, the second
unlicensed device operating on a frequency not permitted to the
second unlicensed device and without complying with regulations,
and the first unlicensed device operating on the licensed TV
frequency with permission and under the regulations, wherein
whether the second unlicensed device complies with the regulations
is determined in consideration of whether the second unlicensed
device is a fixed type device or a portable type device, and
wherein the illegal device detection event in the first unlicensed
device is reported only when the first unlicensed device and the
second device belong to a same type.
8. The enabler entity of claim 7, wherein the event indication
message further comprises: an identification information of the
second unlicensed device; and a channel number on which the second
unlicensed device is operating.
9. The enabler entity of claim 7, wherein the enabler entity
comprises a coexistence enabler (CE), and the manager entity
comprises a coexistence manager (CM).
10. The enabler entity of claim 7, wherein the first unlicensed
device and the second unlicensed device comprise a television band
device (TVBD).
11. The enabler entity of claim 7, wherein the event indication
message transmitted by the RF unit to the manager entity is
transmitted when the second unlicensed device is not served by the
enabler entity.
12. The enabler entity of claim 7, wherein the event indication
message further comprises: a source identifier indicating an
identifier of the enabler entity; and a destination identifier
indicating an identifier of the manager entity.
Description
TECHNICAL FIELD
The present invention relates to a Wireless Local Area Network
(WLAN) system, and more particularly, to a method and apparatus for
de-enabling an illegal device in a WLAN system.
BACKGROUND ART
Standards for WLAN technology have been developed by the Institute
of Electrical and Electronics Engineers (IEEE) 802.11
specifications. IEEE 802.11a and 802.11b use an unlicensed band at
2.4 GHz or 5 GHz. IEEE 802.11b provides a transmission rate of 11
Mbps and IEEE 802.11a provides a transmission rate of 54 Mbps. IEEE
802.11g applies Orthogonal Frequency-Division Multiplexing (OFDM)
at 2.4 GHz to provide a transmission rate of 54 Mbps. IEEE 802.11n
applies Multiple Input Multiple Output (MIMO)-OFDM to provide a
transmission rate of 300 Mbps for four spatial streams. IEEE
802.11n supports a channel bandwidth up to 40 MHz to provide a
transmission rate of 600 Mbps.
Currently, the IEEE 802.11 of standard, which specifies operation
of an unlicensed device in a TV White Space (TVWS) band, is being
developed.
A TVWS includes an Ultra High Frequency (UHF) band and a Very High
Frequency (VHF) band as a frequency allocated to a broadcast TV and
means a frequency band in which an unlicensed device is permitted
to be used under the condition that it does not hinder
communication of a licensed device operating in a corresponding
frequency band. The licensed device may include a TV, a wireless
microphone, etc. The licensed device may be called an incumbent
user or a primary user.
Operation of all unlicensed devices is permitted in frequency bands
of 512 to 608 MHz and 614 to 698 MHz except for a few special
cases. However, in frequency bands of 54 to 60 MHz, 76 to 88 MHz,
174 to 216 MHz, and 470 to 512 MHz, communication only between
fixed devices is permitted. The fixed devices refer to devices
which transmit signals only at a given location. An IEEE 802.11
TVWS terminal refers to an unlicensed device operating using an
IEEE 802.11 Media Access Control (MAC) layer and a physical layer
(PHY) in a TVWS spectrum.
An unlicensed device which desires to use a TVWS should provide a
protection function for a licensed device. Accordingly, the
unlicensed device must confirm whether the licensed device occupies
a corresponding band before starting signal transmission in the
TVWS.
To this end, the unlicensed device should obtain channel list
information usable in a corresponding area by accessing a
geo-location database through the Internet or a dedicated network.
The geo-location database is a database for storing and managing
information of registered licensed devices, geo-locations of the
licensed devices, and channel use information which dynamically
varies over a channel use time.
Alternatively, the unlicensed device may confirm whether a
corresponding band is being used by the licensed device by
performing spectrum sensing. A spectrum sensing mechanism includes
an energy detection scheme and a feature detection scheme. If
strength of a signal received in a specific channel is above a
prescribed value or if a DTV preamble is detected, the unlicensed
device may determine that the licensed device is using the specific
channel. If it is determined that the licensed device is being used
in a channel immediately adjacent to a currently used channel, the
unlicensed device should lower transmission power.
However, there may be unlicensed devices which attempt operation in
an unusable channel or are operating in an unusable channel,
without conforming to regulations. Accordingly, a method for
detecting and then de-enabling such an illegal device is
required.
DETAILED DESCRIPTION OF THE INVENTION
Technical Problems
As described above, since an unlicensed device which desires to use
a white space (e.g. TVWS) should provide a protection function for
a licensed device, a method for detecting and de-enabling the
unlicensed device is required.
It is a technical object of the present invention to provide a
method and apparatus for detecting and de-enabling an illegal
device to protect a licensed device in a white space.
It will be appreciated by persons skilled in the art that the
technical objects that can be achieved through the present
invention are not limited to what has been particularly described
hereinabove and other technical objects of the present invention
will be more clearly understood from the following detailed
description.
Technical Solutions
To achieve the above technical object, in a method for detecting an
illegal device at a first station serving as an unlicensed device
permitted to operate within an available channel which is not used
by a licensed device in a TV White Space (TVWS) band in a wireless
Local Area Network (WLAN) system in accordance with an aspect of
the present invention, the first station receives a first available
channel list from an enabling station of the first station,
receives an enabling signal from a second station, and determines
whether the second station is an illegal device by using the
enabling signal and the first available channel list. The first
station may be a dependent station and the second station may be an
enabling station for controlling the dependent station.
If a channel from which the enabling signal is detected is not
included in the first available channel list, the first station may
determine that the second station is an illegal device in the
determining step.
The first station may receive information about a device type to
which the available channel list is applied from the enabling
station, the enabling signal may include information about a device
type of the second station, and the first station may determine
whether the second station is an illegal device in the determining
step in consideration of the device type to which the available
channel list is applied and the device type of the second
station.
The first station may receive a second available channel list from
a third station, and if the second available channel list is
different from the first available channel list, may determine that
the third station is an illegal device.
The first station may receive, from the enabling station, a request
frame including a monitoring target channel, wherein the enabling
station requests the first station to monitor the monitoring target
channel, and may receive the enabling signal by monitoring the
monitoring target channel.
The request frame may further include a time duration during which
the enabling station requests the first station to perform
monitoring, and the first station may receive an enabling signal
comprises receiving the enabling signal by performing monitoring
during the time duration.
If the second station is an illegal device, the first station may
transmit a report frame to the enabling station, wherein the report
frame includes an address of the second station and a channel from
which the enabling signal is detected.
The first station may receive an address of an enabling station of
the second station, and the report frame may further include the
address of the enabling station of the second station.
To achieve the above technical object, in a method for de-enabling
an illegal device in a first station of a Wireless Local Area
Network (WLAN) in accordance with another aspect of the present
invention, the first station transmits a first available channel
list to a second station, and receives a first report frame
including an address of a third station which is judged to be an
illegal device from the second station, wherein the third station
is a device which is judged to be an illegal device by the second
station using an enabling signal received from the third station
and using the first available channel list. The first station may
be an enabling station and the second station may be a dependent
station controlled by the enabling station.
The first report frame may further include an address of an
enabling station of the third station.
If the enabling station of the third station is identical to the
first station, the first station may transmit a de-enablement frame
for commanding the third station to be de-enabled to the third
station.
The third station may transition to an un-enabled state upon
receiving the de-enablement frame.
If the enabling station of the third station is different from the
first station, the first station may transmit a second report frame
(e.g. TVWS coexistence information frame) including the address of
the third station and the address of the enabling station of the
third station to a Coexistence Manager (CM). The second report
frame may cause the CM to determine whether to de-enable the third
station by using coexistence information of the TVWS coexistence
information frame, and if the CM determines that the third station
be de-enabled, may cause the CM to transmit a de-enablement command
frame (e.g. a TVWS coexistence command frame) including the address
of the third station to the enabling station of the third station.
The enabling station of the third station may transmit a
de-enablement frame for directing the third station to be
de-enabled to the third station.
The second station may determine that the third station is an
illegal device if a channel from which the enabling signal is
detected is not included in the first available channel list.
The first station may transmit information about a device type to
which the first available channel list is applied to the second
station, the enabling signal may include information about a device
type of the third station, and the second station may determine
whether the third station is an illegal device in consideration of
the device type to which the first available channel list is
applied and the device type of the third station.
The first station may transmit a request frame including a
monitoring target channel to request monitoring to the second
station, and the second station may receive the enabling signal by
monitoring the monitoring target channel.
To achieve the above technical object, a first station serving as
an unlicensed device permitted to operate within an available
channel which is not used by a licensed device in a TV White Space
(TVWS) band in a wireless Local Area Network (WLAN) system in
accordance with a further aspect of the present invention includes
a reception module for receiving a first available channel list
from an enabling station of the first station and receiving an
enabling signal from a second station, and a processor for
determining whether the second station is an illegal device by
using the enabling signal and the first available channel list.
Advantageous Effects
According to embodiments of the present invention, a licensed
device can be protected by efficiently detecting and de-enabling an
illegal device using a channel which cannot be used by an
unlicensed device in a TVWS band.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram illustrating an example of the configuration of
a WLAN system.
FIG. 2 is a diagram illustrating another example of the
configuration of a WLAN system.
FIG. 3 is a diagram illustrating an STA enablement procedure.
FIG. 4 is a diagram illustrating a format of a DSE enablement
frame.
FIG. 5 is a diagram illustrating an example of an available TV
channel according to device type.
FIG. 6 is a diagram illustrating an example of a format of a TVBD
measurement request frame transmitted by an enabling STA to request
monitoring to a dependent STA.
FIG. 7 is a diagram illustrating another example of a format of a
TVBD measurement request frame transmitted by an enabling STA to a
dependent STA to request monitoring.
FIG. 8 illustrates a format of a TVBS measurement report frame for
reporting, at a dependent STA, detection of an illegal device to an
enabling STA thereof.
FIG. 9 is a diagram illustrating the case in which an enabling STA
of an illegal device is equal to an enabling STA of a dependent STA
detecting the illegal device.
FIG. 10 is a diagram illustrating the case in which an enabling STA
of an illegal device is different from an enabling STA of a
dependent STA detecting the illegal device.
FIG. 11 is a diagram illustrating a format of a DSE identifier
element.
FIG. 12 is a diagram illustrating a format of a de-enablement
frame.
FIG. 13 is a diagram illustrating a procedure for de-enabling an
illegal device when an enabling STA of the illegal device is
different from an enabling STA of a dependent STA detecting the
illegal device.
FIG. 14 is a diagram illustrating a format of a TVWS coexistence
information frame.
FIG. 15 is a diagram illustrating a format of a TVWS coexistence
command frame.
FIG. 16 is a block diagram illustrating the configuration of a
device which can be applied to an STA or an AP and can implement
the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, exemplary embodiments of the present invention will be
described with reference to the accompanying drawings. It is to be
understood that the detailed description, which will be disclosed
along with the accompanying drawings, is intended to describe the
exemplary embodiments of the present invention, and is not intended
to describe a unique embodiment through which the present invention
can be carried out. The following detailed description includes
detailed matters to provide full understanding of the present
invention. However, it will be apparent to those skilled in the art
that the present invention can be carried out without the detailed
matters.
In some instances, well-known structures and devices are omitted in
order to avoid obscuring the concepts of the present invention and
the important functions of the structures and devices are shown in
block diagram form. The same reference numbers will be used
throughout the drawings to refer to the same or like parts.
First, a general configuration of a WLAN will be described with
reference to FIG. 1 and FIG. 2.
FIG. 1 is a diagram illustrating an example of the configuration of
a WLAN system.
As shown in FIG. 1, the WLAN system includes one or more Basic
Service Sets (BSSs). The BSS refers to a set of stations (STAs)
which are successfully synchronized to communicate with one
another.
The STA is a logical entity that contains a Medium Access Control
(MAC) and a physical layer interface for a wireless medium, and
includes an Access Point (AP) and a non-AP STA. A portable terminal
manipulated by a user among STAs is a non-AP STA. The non-AP STA
may be simply referred to as an STA. The non-AP STA may also be
referred to as a terminal, a Wireless Transmit/Receive Unit (WTRU),
a User Equipment (UE), a Mobile Station (MS), a Mobile Terminal, a
mobile subscriber unit, etc.
The AP is an entity that provides access to a Distribution System
(DS) to an STA associated therewith via a wireless medium. The AP
may be referred to as a centralized controller, a Base Station
(BS), a Node-B, a Base Transceiver System (BTS), a site controller,
etc.
The BSS may be classified into an infrastructure BSS and an
Independent BSS (IBSS).
The BSSs shown in FIG. 1 are IBSSs. The IBSS refers to a BSS which
does not include an AP. Since the IBSS does not include an AP, it
forms a self-contained network in which no access to a DS is
available.
FIG. 2 is a diagram illustrating another example of the
configuration of the WLAN system.
BSSs shown in FIG. 2 are infrastructure BSSs. The infrastructure
BSS includes one or more STAs and APs. Although communication
between non-AP STAs in the infrastructure BSS is basically
performed via an AP, direct communication between the non-AP STAs
may be performed when a direct link therebetween is
established.
As shown in FIG. 2, a plurality of infrastructure BSSs may be
interconnected through a DS. A plurality of BSSs interconnected
through the DS is referred to as an Extended Service Set (ESS).
STAs included in the ESS may communicate with one another. A non-AP
STA may move from one BSS to another BSS while performing seamless
communication within the same ESS.
The DS is a mechanism for connecting a plurality of APs. The DS is
not necessarily a network, and has no format limitation as long as
it can provide a prescribed distribution service. For example, the
DS may be a wireless network such as a mesh network, or may be a
physical structure for interconnecting APs.
Next, a procedure for enabling an STA for operation in a TVWS band
and a procedure for obtaining an available channel list will be
described.
An unlicensed device operating in a TVWS band may be divided into
an enabling STA and a dependent STA. The enabling STA is an STA
that can enable the dependent STA. The enabling STA can transmit
signals without receiving an enabling signal and can initiate a
network.
The enabling STA may register geo-location information in a
database (DB) and acquire a channel list available at a
corresponding geo-location from the DB. The enabling STA is not
necessarily a WLAN STA and may be a logical entity or a network
server which can provide services related to enablement.
The dependent STA is an STA that can transmit signals only upon
receiving an enabling signal and is controlled by the enabling STA.
The dependent STA should be enabled only through the enabling STA
and cannot be independently enabled.
FIG. 3 is a diagram illustrating an STA enablement procedure.
A procedure through which a dependent STA is enabled by an enabling
STA may conform to a procedure similar to Dynamic STA Enablement
(DSE) of IEEE 802.11y.
As shown in FIG. 3, the enabling STA transmits a beacon including a
DSE registered location element (step S310). The DSE registered
location element includes a RegLoc DSE bit set to 1. The enabling
STA may transmit a probe response frame including the DSE
registered location element. A signal indicating that enablement is
possible is called an enabling signal. The beacon or probe response
frame including the DSE registered location element is the enabling
signal.
The dependent STA receiving and decoding the DSE registered
location element may transmit a DSE enablement request frame to the
enabling STA by using a channel indicated by the DSE registered
location element (step S320) and may receive a DSE enablement
response frame from the enabling STA (step S330).
FIG. 4 is a diagram illustrating a format of a DSE enablement
frame. The DSE enablement frame may be a DSE enablement request
frame or a DSE enablement response frame.
As illustrated in FIG. 4, the DSE enablement frame includes a
category field, an action value field, a requester STA address
field, a responder STA address field, a reason result code field,
and an enablement identifier field.
The requester STA address field denotes a MAC address of an STA
transmitting the DSE enablement frame, and the responder STA
address field denotes a MAC address of an STA receiving the DSE
enablement frame. The reason result code field indicates whether
the DSE enablement frame is a DSE enablement request frame or a DSE
enablement response frame. The enablement identifier field denotes
an enablement ID allocated by the enabling STA to the dependent STA
when the DSE enablement frame is the DSE enablement response
frame.
Accordingly, if the DSE enablement frame is the DSE enablement
request frame transmitted by the dependent STA, the requester STA
address field denotes a MAC address of the dependent STA, the
responder STA address field denotes a MAC address of the enabling
STA, the reason result code field indicates that the DSE enablement
frame is the DSE enablement request frame, and the enablement
identifier field is filled with an invalid value.
If the DSE enablement frame is the DSE enablement response frame
transmitted by the enabling STA, the requester STA address field
denotes a MAC address of the enabling STA, the responder STA
address field denotes a MAC address of the dependent STA, the
reason result code field indicates that the DSE enablement frame is
the DSE enablement response frame, and the enablement identifier
field is filled with an enablement ID allocated to the dependent
STA by the enabling STA.
Another enablement method uses a Registered Location Query Protocol
(RLQP). This method performs DSE enablement using a Generic
Advertisement Service (GAS) protocol of IEEE 802.11u. An STA
supporting the GAS protocol includes an interworking element in the
beacon frame and probe response frame. The STA transmits an
advertisement protocol ID supported thereby through an
advertisement protocol element.
In the enablement method using the RLQP, the beacon frame or probe
response frame, which includes the advertisement protocol element
including an advertisement protocol tuple including the protocol ID
indicating the RLQP, is the enabling signal.
Namely, the enabling STA transmits the beacon frame or probe
response frame which includes the advertisement protocol element
including an advertisement protocol tuple including the protocol ID
indicating the RLQP. The dependent STA transmits a DSE enablement
request element using the GAS protocol upon receiving the beacon
frame or probe response frame and is enabled upon receiving the DSE
enablement response element from the enabling STA.
In order for an STA to operate in a white space band (e.g. TVWS
band), a protection scheme for a licensed device should first be
provided. Accordingly, the STA should find an available channel,
which is not used by a licensed device and therefore can be used by
an unlicensed device, and then operate in the available
channel.
The STA may determine TV channel availability using a spectrum
sensing method and a TV channel schedule identifying method through
access to a DB. DB information includes information about a usage
schedule of a specific channel of a licensed device at a specific
location. Accordingly, an STA which desires to discern TV channel
availability should acquire DB information based on its location
information by accessing a DB via the Internet and this action
should be performed in a time unit sufficient to protect the
licensed device.
The enabling STA informs the dependent STA of whether a channel of
a TV signal is occupied and which channels can be used by the
unlicensed device. That is, the enabling STA transmits an available
channel list to the dependent STA. Channels included in the
available channel list are channels not used by signals which
should be legally protected signals and are available to the
unlicensed device when the unlicensed device accesses the DB.
The channels of the available channel list may have granularity of
a minimum unit provided by the DB. Namely, if a channel of a
minimum unit provided by a TV band DB for a TVWS is a TV channel,
the available channel list is a list of TV channels which are
available to the unlicensed device. For example, in the U.S. and
Korea, the TV channel list may be a list of channels in units of 6
MHz and in other countries, it may be a list of channels in units
of 7 MHz or 8 MHz.
The available channel list may be transmitted to the dependent STA
from the enabling STA during the enablement procedure or after
enablement is successfully performed.
Next, a method for de-enabling an illegal device in a WLAN system
according to an exemplary embodiment of the present invention will
be described.
According to the embodiment of the present invention, if the
dependent STA reports an illegal device detected thereby to the
enabling STA, the enabling STA de-enables the illegal device.
Accordingly, a procedure for detecting and reporting an illegal
device, performed by the dependent STA, will first be
described.
An illegal device refers to a white space band device, for example,
a TV Band Device (TVBD) which attempts to operate in an unavailable
channel or is operating in an unavailable channel, without
conforming to regulation. For instance, a dependent STA may occupy
an unlicensed channel in a geo-location thereof through an
intentional method such as fake registration. In addition, location
information of a specific AP may be wrongly registered due to an
error of a GPS receiver, an insufficient GPS signal, a GPS jammer,
etc. so that the AP may obtain incorrect available channel
information. Such illegal dependent AP may transmit an enabling
signal in an unlicensed channel irrespective of a scheme of the
enablement procedure. At this time, an unlicensed channel used by
an illegal TVBD may be an illegal channel. In other words, the
unlicensed channel may be a channel, use of which is limited by
regulation or may be a channel used by a licensed device at a
corresponding time.
Dependent STAs which are normally operating may detect enabling
signals in various types of measurement and monitoring procedures
including a DSE measurement procedure. The dependent STAs determine
whether the detected enabling signals are legal. If it is
determined that an unlicensed frequency band is used, the dependent
STAs may report this fact to enabling STAs.
There may be many methods through which the dependent STA judges
the legality of an enabling signal, typically including (1) a
method for voluntarily judging, at the dependent STA, the legality
of an enabling signal received using an available channel list
belonging to the dependent STA, and (2) a method for commanding, at
the enabling STA, the dependent STA to perform monitoring as to
whether an illegal device for specific channels is present.
First, the method for voluntarily judging, at the dependent STA,
the legality of an enabling signal received using an available
channel list belonging to the dependent STA will now be
described.
A dependent STA which normally operates may obtain an available
channel list from an enabling STA during an enablement procedure or
after the enablement procedure is successfully performed. If the
obtained available channel list is valid, the dependent STA may
detect an illegal device using the obtained available channel
list.
The dependent STA may judge the legality of an STA which has
transmitted an enabling signal by receiving the enabling signal or
may judge the legality of an STA which has transmitted an available
channel list by receiving the available channel list.
The method for judging the legality of an STA which has transmitted
an enabling signal by receiving the enabling signal will now be
described. The dependent STA may monitor one or more channels while
performing a normal operation or during a time duration designated
to monitor channels. At this time, the dependent STA may monitor
not only channels included in the available channel list but also
channels which are not included in the available channel list and
may receive an enabling signal in a specific channel while
performing monitoring. The dependent STA compares a channel from
which the received enabling signal is detected with channel
information of the available channel list belonging thereto. If the
channel from which the received enabling signal is detected is not
included in the available channel list, the dependent STA may
determine that the STA which has transmitted the corresponding
enabling signal is an illegal device.
Next, the method for judging the legality of an STA which has
transmitted an available channel list by receiving the available
channel list will be described. The dependent STA may determine
whether an STA which has transmitted an available channel list is
an illegal device by receiving the available channel list from an
STA other than an enabling STA thereof. The dependent STA may
acquire the available channel list during an enablement procedure
or after the enablement procedure is successfully performed. The
dependent STA may obtain a first available channel list from an
enabling STA thereof and may obtain a second available channel list
from an STA other than the enabling STA. In other words, the
dependent STA may acquire the available channel lists from the
different two STAs. If the second available channel list is
different from the first available channel list, the dependent STA
may judge that the STA which has transmitted the second available
channel list is an illegal device.
An example of an illegal device detection procedure is described
when the dependent STA detecting an illegal device is a non-AP STA.
The non-AP STA may receive an available channel list from an AP
associated therewith. The AP may register a geo-location thereof in
a DB or an enabling STA and may obtain the available channel list
at a corresponding location. The AP may transmit the available
channel list thereof to a non-AP STA. In this case, the non-AP STA
corresponds to an STA, of which FCC ID is proved to be valid by the
AP by accessing the DB. That is, the non-AP STA periodically
receives the available channel list from the AP associated
therewith and may obtain the available channel list from the
enabling STA periodically or when necessary. If the available
channel list received from the AP associated with the non-AP STA is
not equal to the available channel list received from the enabling
STA, the non-AP STA may determine that the AP associated therewith
is an illegal device.
In addition, when determining whether a specific STA is an illegal
device, the dependent STA may use information as to which device
types are included in the available channel list belonging thereto
and which device type the specific STA is.
Namely, in order to judge the legality of a specific STA using an
enabling signal received from the specific STA, the dependent STA
should be aware of which device types are included in the available
channel list belonging thereto and which device type the specific
STA which has transmitted the enabling signal is.
The device type refers to a type of a TV band device which is
defined according to which channel bands are permitted to be used
by TV band devices operating in a TVWS band and according to types
of supported spectrum mask classes.
This is because frequency bands permitted for use differ according
to devices by regulations, or an available channel number and a
maximum transmission power value in a corresponding channel may be
variously changed due to variation of spectrum mask classes
supported by devices even if the permitted frequency bands are not
different.
The enabling STA or AP may inform the dependent STA of which device
types an available channel list includes so that the dependent STA
may identify to which device type the obtained available channel
list is applied. Desirably, the enabling STA or AP may transmit
information as to which device types the available channel list
includes while transmitting the available channel list to the
dependent STA.
The dependent STA may receive an enabling signal from a channel
which is not included in the available channel list belonging
thereto. However, the STA transmitting the enabling signal may be
permitted to use a corresponding channel according to device type.
Accordingly, the STA transmitting the enabling signal may include a
device type thereof in the enabling signal so that the dependent
STA may consider a device type of the STA transmitting the enabling
signal. If the enabling signal includes the available channel list,
the STA transmitting the enabling signal may include a device type
in the available channel list. If the enabling signal does not
include the available channel list, the STA transmitting the
enabling signal may add a device type field to the enabling signal
or may transmit signaling indicating a device type together with
the enabling signal.
FIG. 5 is a diagram illustrating an example of an available TV
channel according to device type. For example, the device type may
include a fixed device and a personal/portable device. FIG. 5(a)
shows available channels and a maximum power value of the fixed
device and FIG. 5(b) shows available channels and a maximum power
value of the personal/portable device.
For example, 18 channels in 54 to 60 MHz, 76 to 88 MHz, 174 to 216
MHz, and 470 to 512 MHz are permitted to be used only by the fixed
device and 30 channels in 512 to 608 MHz and 614 to 698 MHz are
permitted to be used by both the fixed device and personal/portable
device, by FCC regulation. In addition, the fixed device cannot use
a channel right next to a TV channel which is being used by a
licensed device. However, the personal/portable device may use a
channel right next to a TV channel which is being used by a
licensed device under the condition of reducing an allowable
maximum power value from 100 mW to 40 mW. Therefore, available
channels vary according to device type as shown in FIG. 5.
When the dependent STA receives an enabling signal from a second AP
in a monitoring procedure during a normal operation in association
with a first AP, if the received enabling signal has been
transmitted through a channel used by a license device, the
dependent STA may determine that the second AP is an illegal device
regardless of a device type to which an available channel list
belonging thereto is applied and a device type of the second
AP.
However, since availability of a channel and a maximum power value
may vary according to device type even though the channel is not
occupied by a licensed device, if the dependent STA receives the
enabling signal from the second AP in a channel other than the
channel occupied by a licensed device, it may be desirable to
determine whether the second AP is an illegal device in
consideration of a device type to which an available channel list
belonging to the dependent STA is applied and a device type of the
second AP.
For example, assuming that a device type of the available channel
list belonging to the dependent STA is a fixed device, even when
the dependent STA receives the enabling signal from the second AP
in a channel number 22 or 24, if the device type of the second AP
included in the received enabling signal is a personal/portable
device, the dependent STA determines that the second AP is not an
illegal device.
Assuming that a device type of the available channel list belonging
to the dependent STA is a personal/portable device, even when the
dependent STA receives the enabling signal from the second AP in a
channel number 19, if the device type of the second AP included in
the received enabling signal is a fixed device, the dependent STA
determines that the second AP is not an illegal device.
Next, the method for commanding, at the enabling STA, the dependent
STA to perform monitoring as to whether an illegal device for
specific channels is present will be described.
The enabling STA may request the dependent STA to monitor an
enabling signal in specific channels. A frame transmitted by the
enabling STA to the dependent STA to request monitoring may
designate a monitoring target channel list and a monitoring time
duration. Since monitoring target channels are occupied by a
licensed device rather than by available channels, they may be
channels which can be used by an unlicensed device at a
corresponding time. Upon receiving an enabling signal from the
monitoring target channel, the dependent STA may determine that an
STA transmitting the received enabling signal is an illegal
device.
FIG. 6 is a diagram illustrating an example of a format of a TVBD
measurement request frame transmitted by an enabling STA to a
dependent STA to request monitoring. FIG. 7 is a diagram
illustrating another example of a format of a TVBD measurement
request frame transmitted by an enabling STA to request monitoring
to a dependent STA. In FIG. 6, a channel that the enabling STA
requests the dependent STA to monitor is indicated by a WLAN
channel. In FIG. 7, a channel that the enabling STA requests the
dependent STA to monitor is indicated by a TV channel.
As shown in FIG. 6, the TVBD measurement request frame may include
a category field, an action value field, a requester STA address
field, a responder STA address field, an operating class field, a
channel number field, a measurement start time field, and a
measurement duration field.
Alternatively, the TVBD measurement request frame may include, as
shown in FIG. 7, a category field, an action value field, a
requester STA address field, a responder STA address field, a TV
channel number field, a measurement start time field, and a
measurement duration field.
The measurement start time field indicates when an STA starts
monitoring and the measurement duration field denotes a time
duration during which the STA performs monitoring.
The operating class field and the channel number field denote a
number of a WLAN channel that the enabling STA requests the
dependent STA to monitor. The TV channel number field denotes a
number of a TV channel that the enabling STA requests the dependent
STA to monitor. In this case, the dependent STA receives an
enabling signal to detect an illegal device by monitoring the WLAN
channel designated by the operating class field and the channel
number field or monitoring the TV channel indicated by the TV
channel number field.
Alternatively, the enabling STA may request the dependent STA to
monitor channels except for the WLAN channel designated by the
operating class field and the channel number field of FIG. 6. The
enabling STA may also request the dependent STA to monitor channels
except for the TV channel designated by the TV channel number field
of FIG. 7. In this case, the dependent STA may receive an enabling
signal to detect an illegal device by monitoring WLAN channels
except for the WLAN channel designated by the operating class field
and the channel number field or monitoring TV channels except for
the TV channel designated by the TV channel number field.
Even when the enabling STA requests the dependent STA to monitor an
enabling signal in specific channels, it is desirable that the
dependent STA be aware of a device type of an available channel
list belonging thereto and a device type of an STA which has
transmitted the enabling signal received in a monitoring procedure.
Accordingly, a device type is desirably included in the available
channel list obtained by the dependent STA or information about a
device type to which the available channel list is applied is
desirably transmitted to the dependent STA. It is also desirable
that a device type of the STA which has transmitted the enabling
signal be included in the enabling signal.
Upon detecting an illegal device, the dependent STA may report
detection of the illegal device to the enabling STA.
The report message may include a MAC address of an illegal device,
an address of an enabling STA of the illegal device, and an illegal
channel number. The illegal channel refers to a channel which is
being illegally used by the illegal device.
If the enabling STA commands the dependent STA to perform
monitoring as to whether an illegal device for specific channels is
present, the report message may be transmitted as a response to the
TVBD measurement request frame. If the dependent STA has detected
the illegal device without request of the enabling STA, the
dependent STA may autonomously transmit the report message.
FIG. 8 illustrates a format of a TVBS measurement report frame for
reporting, at a dependent STA, detection of an illegal device to an
enabling STA thereof.
As shown in FIG. 8, the TVBD measurement report frame may include a
category field, an action value field, a requester STA address
field, a responder STA address field, a measurement start time
field, a measurement duration field, an illegal TVBD address field,
an enabling STA address of illegal TVBD field, and an illegal TVBD
channel number field.
The illegal TVBD address field denotes an address of an STA
determined as an illegal device by the dependent STA. In other
words, the illegal TVBD address field indicates an address of an
illegal TVBD which is using a TVWS band not permitted to be used by
regulation.
The enabling STA address of illegal TVBD field denotes an address
of an enabling STA of an STA determined as an illegal device by the
dependent STA.
The illegal TVBS channel number field denotes a channel number
which is being illegally used by an STA determined as an illegal
device by the dependent STA.
As an example, a TV channel number list may be used as a value of
the illegal TVBD channel number field. If the enabling STA commands
the dependent STA to monitor a WLAN channel, the dependent STA may
check to which TV channel a WLAN channel detecting an illegal
device corresponds and may report the corresponding TV channel
number to the enabling STA. If the enabling STA commands the
dependent STA to monitor a TV channel, the dependent STA may report
a TV channel number in which an illegal device is detected to the
enabling STA.
Next, a procedure through which the enabling STA de-enables an
illegal device will be described.
A de-enablement procedure may differ according to whether an
enabling STA of an illegal device is equal to an enabling STA of a
dependent STA detecting the illegal device. Accordingly, in an
exemplary embodiment of the present invention, description will be
given of a de-enablement procedure when the enabling STA of the
illegal device is equal to the enabling STA of the dependent STA
detecting the illegal device and a de-enablement procedure when the
enabling STA of the illegal device is different from the enabling
STA of the dependent STA detecting the illegal device.
FIG. 9 is a diagram illustrating the case in which an enabling STA
of an illegal device is equal to an enabling STA of a dependent STA
detecting the illegal device, and FIG. 10 is a diagram illustrating
the case in which an enabling STA of an illegal device is different
from an enabling STA of a dependent STA detecting the illegal
device.
To determine whether an enabling STA of an illegal device is equal
to an enabling STA of a dependent STA detecting the illegal device,
it is desirable that information about the enabling STA of the
illegal device be broadcast. In FIG. 9 and FIG. 10, a dependent STA
receives an enabling signal from a dependent AP 1 corresponding to
an illegal TVBD. When the dependent STA is not aware of information
about an enabling STA of the dependent AP 1 and transmits a frame
which does not include the information about the enabling STA, if
the enabling STA receiving the information is not an STA enabling
an illegal TVBD, the enabling STA cannot direct de-enablement of
the corresponding illegal TVBS. Accordingly, the dependent STA
should be able to confirm to which enabling STA the illegal TVBD is
connected.
To this end, a method for explicitly indicating an enabling STA is
needed. In the exemplary embodiment of the present invention, it is
proposed that the dependent STA broadcast a DSE identifier element
including an address of an enabling STA enabling the dependent STA.
If the dependent STA transmitting the DSE identifier element is an
AP, the DSE identifier element may be included in a beacon frame or
a probe response frame.
FIG. 11 is a diagram illustrating a format of a DSE identifier
element. As shown in FIG. 11, the DSE identifier element may
include an element ID field, a length field, an enabling STA
address field, and an enabling STA timestamp field.
The enabling STA address field denotes an address of an enabling
STA which enables an STA transmitting the DSE identifier element.
The enabling STA timestamp field denotes a timestamp of an enabling
STA for time synchronization between an enabling STA, a dependent
AP, and a dependent STA associated with the AP.
First, a procedure for de-enabling an illegal device when an
enabling STA of the illegal device is identical to an enabling STA
of a dependent STA detecting the illegal device will now be
described.
The dependent STA which has detected an illegal device may transmit
a report message to an enabling STA thereof. Upon receiving the
report message, the enabling STA may determine whether to de-enable
the illegal device using additional information (e.g. information
as to whether the illegal device is connected thereto or
information as to whether to de-enable a CM which will be described
later). If the enabling STA determines that the illegal device
should be de-enabled, the dependent STA may direct the enabling STA
to transmit a de-enablement frame to the illegal device using a MAC
address of the illegal device included in the received massage.
Upon receiving the de-enablement frame, the illegal device may stop
transmission in a corresponding channel and transition to an
un-enabled state.
In FIG. 9, if the dependent STA receives an enabling signal from
the dependent AP 1 and judges that the dependent AP 1 is an illegal
device by using the enabling signal, the dependent STA may transmit
a report message including a MAC address of the dependent AP 1 to
an enabling STA (enabler). Upon receiving the report message, the
enabler may determine whether to de-enable the dependent AP 1
through additional information. If it is determined that the
dependent AP 1 should be de-enabled, the enabler may transmit a
de-enablement frame to the dependent AP 1 using a MAC address in
the report message. Upon receiving the de-enablement frame, the
dependent AP 1 may stop transmission in a corresponding channel and
transition to an un-enabled state.
The de-enablement frame may use, for example, the same format as a
de-enablement frame proposed in IEEE 802.11y. FIG. 12 is a diagram
illustrating a format of a de-enablement frame.
Next, a procedure for de-enabling an illegal device when an
enabling STA of the illegal device is different from an enabling
STA of a dependent STA detecting the illegal device will be
described with reference to FIG. 13 to FIG. 15.
FIG. 13 is a diagram illustrating a procedure for de-enabling an
illegal device when an enabling STA of the illegal device is
different from an enabling STA of a dependent STA detecting the
illegal device.
In FIG. 13, a Coexistence Manager (CM) is an entity which can
perform resource assignment in order to solve an inference problem
between Coexistence Enablers (CEs) connected thereto while
including an interface with a DB and providing policy and
guidelines associated with coexistence, for coexistence between
different systems operating in a TVWS and an enterpriser. A CE is
an entity serving to transmit requests and information received
from the CM to a TVBD through an interface with the TVBD. In the
exemplary embodiment of the present invention, a structure
including a management server such as a CM is assumed as a high
layer entity which can control a plurality of enabling STAs.
Upon detecting an illegal device, the dependent STA may transmit a
report message to an enabling STA (enabler 2) thereof. If the
enabler 2 receiving the report message is not an enabling STA of
the illegal device, the enabler 2 may transmit a TVWS coexistence
information frame in order to report information about the illegal
device to the CM.
The TVWS coexistence information frame is an information frame
defined for coexistence between different systems in a TVWS and an
enterpriser and may include an information type field indicating
which information the frame is about.
The TVWS coexistence information frame for reporting an illegal
device may include a MAC address of the illegal device, an address
of an enabling STA of the illegal device, and a channel list which
is illegally used by the illegal device, which are information
included in a report message received by the enabling STA from the
dependent STA, and may include information of a dependent STA which
has detected the illegal device and an enabling STA receiving a
report message from the dependent STA which has detected the
illegal device.
FIG. 14 is a diagram illustrating a format of a TVWS coexistence
information frame.
As shown in FIG. 14, the TVWS coexistence information frame may
include an information type field, a length field, a requester STA
address field, a responder STA address field, an actual measurement
start time field, a measurement duration field, a policed TVBD
address field, an enabling STA address of policed TVBD field, an
illegal TVBD address field, an enabling STA address of illegal TVBD
field, and an illegal TVBD channel number field.
The information type field indicates that the TVWS coexistence
information frame is a frame for reporting detection of an illegal
device. The requester STA address field denotes an address of a CE
transmitting the TVWS coexistence information frame. The responder
STA address field denotes an address of a CM receiving the TVWS
coexistence information frame. The actual measurement start time
field denotes an actual start time of a duration during which
channel measurement is performed to detect the illegal device. The
measurement duration field denotes a duration during which channel
measurement is performed to detect the illegal device.
The policed TVBD address field denotes an address of a TVBD
detecting the illegal device. The enabling STA address of policed
TVBD field denotes an enabling STA of a TVBD detecting the illegal
device. The illegal TVBD address field denotes an address of the
illegal device using a TVWS spectrum which is not permitted to be
used by regulation. The enabling STA address of illegal TVBD field
denotes an address of an enabling STA of the illegal device. The
illegal TVBD channel number field denotes a channel number for a
TVWS spectrum which is being illegally used by the illegal
device.
Upon receiving the TVWS coexistence information frame, the CM
checks the information type field to confirm whether the received
TVWS coexistence information frame is a report for detection of the
illegal device and may determine whether to de-enable the illegal
device using additional information (e.g. coexistence information).
If it is determined that the illegal device should be de-enabled,
the CM confirms information of the illegal device included in the
TVWS coexistence information frame to transmit a TVWS coexistence
command to the enabling STA of the illegal device. The TVWS
coexistence command frame is a command frame defined for
coexistence between different systems in a TVWS and an enterpriser
and may include a command type field indicating which command the
command frame is about. The TVWS coexistence command frame for
de-enabling the illegal device may include information about the
illegal device.
FIG. 15 is a diagram illustrating a format of a TVWS coexistence
command frame.
As shown in FIG. 15, the TVWS coexistence command frame may include
a command type field, a length field, a requester STA address
field, a responder STA address field, an actual measurement start
time field, a measurement duration field, a policed TVBD address
field, an enabling STA address of policed TVBD field, an illegal
TVBD address field, and an illegal TVBD channel number field.
The command type field indicates that the corresponding TVWS
coexistence command frame is a frame for de-enabling an illegal
device. The requester STA address field indicates an address of a
CM transmitting the TVWS coexistence command frame. The responder
STA address field indicates an address of a CE receiving the TVWS
coexistence command frame, i.e. an address of an enabling STA of
the illegal device. The actual measurement start time field
indicates an actual start time of a duration during which channel
measurement is performed to detect the illegal device. The
measurement duration field indicates a duration during which
channel measurement is performed to detect the illegal device.
The policed TVBD address field indicates an address of a TVBD
detecting the illegal device. The enabling STA address of policed
TVBD field indicates an enabling STA of a TVBD detecting the
illegal device. The illegal TVBD address field indicates an address
of the illegal device using a TVWS spectrum which is not permitted
to be used by regulation. The illegal TVBD channel number field
indicates a channel number for a TVWS which is being illegally used
by the illegal device.
Upon receiving the TVWS coexistence command frame, an enabling STA
checks the command type, and if it is confirmed that the TVWS
coexistence command frame is for de-enabling the illegal device,
the enabling STA may transmit a de-enablement frame to the illegal
device by confirming the illegal TVBD address field. Upon receiving
the de-enablement frame, the illegal device may stop transmission
in a corresponding channel and transition to an un-enabled
state.
FIG. 16 is a block diagram illustrating the configuration of a
device which can be applied to an STA or an AP and can implement
the present invention. As shown in FIG. 16, a device 100 includes a
processor 101, a memory 102, a Radio Frequency (RF) unit 103, a
display unit 104, and a user interface unit 105.
A layer of a physical interface protocol is performed in the
processor 101. The processor 101 provides a control plane and a
user plane. A function of each layer may be performed in the
processor 101.
The memory 102 is electrically connected to the processor 101 and
stores operating systems, application programs, and general
files.
If the device 100 is a user equipment, the display unit 104 may
display various information and may be implemented using a known
Liquid Crystal Display (LCD), an Organic Light Emitting Diode
(OLED), etc. The user interface unit 105 may be combined with a
known user interface such as a keypad, a touchscreen, etc.
The RF unit 103 is electrically connected to the processor 101 and
transmits or receives radio signals. The RF unit 103 may include a
transmission module and a reception module.
The transmission module may be scheduled from the processor 101 to
perform prescribed coding and modulation upon signals and/or data
to be transmitted to the exterior and may transmit the coded and
modulated signals and/or data to antennas. A transmitter of a
dependent AP transmits a DSE registered location element, and a DSE
link identifier element including a MAC address of an enabling STA
to a dependent STA. A transmitter of the dependent STA transmits a
DSE enablement request frame to an enabling STA.
The reception module may perform decoding and demodulation upon
radio signals received through external antennas to restore the
radio signals to original data and may transmit the restored data
to the processor 101.
The detailed description of the exemplary embodiments of the
present invention disclosed as described above has been presented
to enable any person of ordinary skill in the art to make and
practice the present invention. Modifications to the preferred
embodiment will be readily apparent to those of ordinary skill in
the art, and the disclosure set forth herein may be applied to
other embodiments and applications without departing from the
spirit and scope of the present invention and the appended claims.
Thus, the present invention is not intended to be limited to the
embodiments described, but is to be accorded the broadest scope
consistent with the claims appended hereto and the disclosure set
forth herein.
INDUSTRIAL APPLICABILITY
Although the various embodiments of the present invention have been
described based on the IEEE 802.11 system, they may be applied in
the same way to a variety of mobile communication systems which can
operate by acquiring available channel information by an unlicensed
device.
* * * * *